JPH0234663A - Polyphenylene sulfide film - Google Patents

Abstract

PURPOSE:To obtain the title film improved in hot dimensional stability and transparency by giving a specified density value and a specified oligomer content value to the film. CONSTITUTION:An at least unidirectionally oriented film containing at least 70mol%, desirably at least 80mol% p-phenylene sulfide units, wherein the density is 1.340, desirably at least 1.350, more desirably 1.355 or above, and the oligomer content is 1.2wt.% or below, desirably 1.0wt.% or below. In order to increase the film density to 1.340 or above, it is preferable to adopt a process comprising heating the film to a temperature from 250 deg.C to the m.p. of the polymer after being oriented. To decrease the oligomer content, the polymer is extracted after production or molded with a vented extruder. This polyphenylene sulfide film is excellent in chemical stability, electrical properties and weathering resistance as well as in hot dimensional stability and mechanical stability.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to polyphenylene sulfide films.

More specifically, the present invention relates to a polyphenylene sulfide film having excellent mechanical strength and heat resistance.

[Problems to be solved by conventional technology and invention]

Conventionally, polyethylene terephthalate film has been commonly used as a general-purpose industrial film, but in recent years, there has been a demand for a film with particularly improved heat resistance.

Aromatic polyamide films and polyimide films are known as typical highly heat-resistant films, but the starting materials for these are expensive, and the so-called casting method must be used as a film forming method. This will result in extremely high costs.

On the other hand, polycarbonate, polyester carbonate, polysulfone, polyetherimide, polyether sulfone, etc. are known as materials to which the melt film forming method, which is advantageous in terms of film forming cost, can be applied and which have relatively excellent heat resistance. , these are all inferior and therefore lack mechanical strength when made into a film.

Therefore, there is currently a strong demand for a film that is relatively inexpensive and has excellent heat resistance and mechanical properties, and a film that has the potential to achieve this purpose is poly-p-phenylene sulfide (hereinafter abbreviated as PPS). ) film is attracting attention.

Regarding this PPS film, for example, Tokukosho! Wow!
0 Tata issue, Tokko Akira! Tar No. 3700, Special Publication Show 3
The film forming conditions are described in 9-j/θ/, etc., and typical film properties such as thermal properties, mechanical properties, electrical properties, etc. are also known.

However, when such a PPS film is actually manufactured,
In order to use it as a base film, several problems must be overcome.

In order to improve the heat-resistant dimensional stability of a PPS film, methods of heat-treating under specific conditions during film formation are disclosed, for example, in Japanese Patent Publication No. 197-J-099 and Japanese Patent Application Laid-open No. 77-20.
This method has been proposed in Japanese Patent Application Laid-Open No. 1//l'', Japanese Patent Application Laid-Open No. 1997-20♂O/R, etc.

However, although the heat-resistant dimensional stability of the films obtained by these methods is improved to some extent, on the other hand, the oligomers present in the polymer bleed out to the film surface due to such heat treatment, resulting in a decrease in the transparency of the film. Furthermore, during film production or processing, problems such as oligomers migrating from the film surface and contaminating equipment often occur.

[Means for solving problems]

As a result of intensive studies to solve the above-mentioned problems, the inventor of the present invention has found that a film having a film density of a certain value or more and an oligomer content of a certain amount or less has excellent heat-resistant dimensional stability and transparency. The gist of the present invention is to provide a polyphenylene sulfide film stretched at least uniaxially, in which 70 moles or more of the film contains repeating units -(-
Composed of o-8-woo, with a density of 7.34tθ or more,
The polyphenylene sulfide film is characterized in that the amount of oligomers contained is 2% by weight or less.

The present invention will be explained in more detail below.

In order to simultaneously and highly satisfy heat resistance and mechanical properties, the PPS composition used in the present invention must ultimately contain p-phenylene sulfite units of 7θ mol or more, and preferably It is 10 molti or more.

Examples of PPS compositions that can be used in the present invention include (1) polymers mainly composed of PPS, (2) PPS
copolymer, (3) a blend of a polymer mainly composed of PPS and a PPS copolymer, (4) a polymer containing m-phenylene sulfide as a main repeating unit, and (1
) or a blend with (2).

The term "polymer mainly composed of PPS" as used herein refers to polyphenylene sulfide containing 0 mol or more of p-7 nylene sulfide units. In addition, PP referred to in the present invention
As an S copolymer, some of the repeating units are, for example, t(X
SOz+S-1 refers to poly p-phenylene sulfide combined with SOz+S-1. In the present invention, polymers mainly composed of PPS are preferred because they have particularly excellent heat resistance. A blend of a polymer mainly composed of PPS and a PPS copolymer is preferably used because it can improve properties.

Examples of the latter blends include the following (1) and (2).
Polyphenylene sulfide containing preferably less than 20 moles, more preferably co-10 moles of m-phenylene sulfide units obtained by friending two types of polyphenylene sulfides () is mentioned.

(1) m-phenylene sulfite unit t"/-t mol-
Polyphenylene sulfide containing (2) p-phenylene sulfide) Polyphenylene sulfide containing 1-t-9t mole or more Especially when producing a thin film with a thickness of 70 μm or less, it is necessary to have excellent film formability. Therefore, the above (1) and (
Blends with 2) are preferably used. Of course, other PPS compositions may be used as long as they do not impair the spirit of the present invention.

Various methods are exemplified as methods for polymerizing these PPSs used in the present invention, but the following methods are usually preferably employed.

That is, an alkali sulfide, especially sodium sulfide, the corresponding dihalobenzene (e.g., p-dichlorobenzene), and optionally a halogen-substituted monomer providing other repeating units are polymerized in an amide polar solvent such as N-methylpyrrolidone. This method involves reacting in the presence of a chemical agent at high temperature and under high pressure.

Conventionally, as a method of increasing the viscosity of PPS, a method of heat-treating PPS at a temperature of 2θ0° C. to the melting point of the polymer in the presence of oxygen to crosslink it is generally known. However, when a polymer whose viscosity has been increased by such a method is used as a film raw material, gases such as S02 are generated, especially during melting.

Further, since the melted state becomes non-uniform, problems such as unevenness occur in the obtained film arise. Therefore, in the present invention, it is preferable not to use such a method of thickening by heat treatment.

The present inventor has discovered that a polymer having a high viscosity by containing a trifunctional unit that allows the polymer chain to branch, preferably from 0.1 molty to 5 molty, more preferably from 0.2 molty to 3 molty, is the present invention. It was found that it is suitable for the invention. Examples of the trifunctional unit include the following, and seven or more of these may be contained. Among them, in order to contain units for reactivity, cost, etc., a trifunctional compound (for example, 2.'it-trichlorobenzene) corresponding to the seven types of halogen-substituted monomers described above may be added and reacted. . In addition, in the present invention, the viscosity suitable for film formation is the melt viscosity at 300°C, S
A method for producing a film using PPS having a zero-order K of OO poise or more and 200,00 θ poise or less will be described.

In the present invention, such PPS is supplied to a well-known melt extrusion device such as an extruder, and heated to a temperature equal to or higher than the melting point of the composition to melt it. Then melted PPS
The material is extruded through a slot-shaped die and rapidly cooled and solidified on a rotating cooling drum to a temperature below the glass transition temperature to obtain an unoriented sheet in a substantially amorphous state. In this case, in order to improve the flatness of the sheet, it is necessary to increase the adhesion between the sheet and the rotating cooling drum, and in the present invention, an electrostatic application adhesion method and/or a liquid application adhesion method are preferably employed.

The electrostatic application contact method usually involves placing a linear electrode on the upper surface of the sheet in a direction perpendicular to the flow of the sheet. ~1
In this method, a DC voltage of 0 Kv is applied to impart an electrostatic charge to the sheet, thereby improving its adhesion to the drum. In addition, the liquid application adhesion method is a method that improves the adhesion between the drum and the sheet by uniformly applying a liquid to the entire or part of the surface of the rotating cooling drum (for example, only the parts that contact both ends of the sheet). be. In the present invention, both may be used in combination if necessary. In the present invention, it is necessary to stretch the sheet thus obtained at least in the axial direction. Stretching methods include longitudinal stretching using the difference in circumferential speed between rolls,
The tenter method or the Cheapler method may be employed.

Specifically speaking about the stretching conditions, the unstretched sheet is preferably heated at 70 to 720°C, more preferably ♂0 to i
The film is stretched 92 to 6 times in one direction using a roll or tenter type stretching machine in a temperature range of ot°C. Also, further/
Preferably 70~/410°C in the direction perpendicular to the steps, more preferably ? In the temperature range of θ~/-2θ℃/,! ~6
It is also possible to obtain a co-axis oriented film by stretching it twice. It is also possible to simultaneously coaxially stretch the unstretched sheet so that the area magnification becomes 3 to 30 times. Although it depends on the use, it is usually preferable to use a coaxially stretched film in terms of heat-resistant dimensional stability and mechanical strength anisotropy.

The stretched film obtained in this way is preferably heat-treated mainly to improve dimensional stability, but if necessary, it may be stretched again in the longitudinal and/or transverse directions before or after the heat treatment to increase orientation and improve mechanical strength. It is also possible to improve it further.

By appropriately selecting the above methods, it is possible to obtain a film oriented in at least the / axis, but in the present invention, it is necessary that the density force of the film be at least /,3/ltO. To 3! O or more, more preferably /, 33! That's all. The density of the film is 34t
If it is less than 0, the heat resistance and dimensional stability will be deteriorated, which is not preferable. In order to make the density of the film 34t0 or more, in the film forming process, after stretching, limited shrinkage or elongation is performed within 20%, or at a constant length, preferably 2g at a temperature of 0°C or more and below the melting point of the polymer, and further Preferably 2! O
A method in which the heat treatment is carried out at a temperature of .degree. C. or above and below the melting point of the polymer is preferably employed. Note that the heat treatment may be performed at the λ stage or higher. When heat treatment is performed at λ stage or higher,
At least/step thereof is preferably performed at a temperature of 24tθ°C or higher and lower than the melting point of the polymer, more preferably 2!0°C.
The above is carried out at a temperature below the melting point of the polymer.

Thus, the film of the present invention can be obtained as a film with excellent heat-resistant dimensional stability, but another feature of the film is that the amount of oligomer contained is below a certain value.In other words, the amount of oligomer in the film is below λ It is necessary that the amount is less than or equal to 0% by weight, and preferably less than 0% by weight.

In the present invention, in order to obtain a film with excellent heat resistance and dimensional stability, heat treatment is performed under the above-mentioned severe conditions to obtain a film with high density, that is, high crystallinity.
Even in such films, if the amount of oligomers contained in the film exceeds 7.2% by weight, the oligomers may bleed out onto the film surface, reducing the transparency of the film or causing problems during the film manufacturing process or during film processing. This is not preferable because the oligomers migrate from the film surface and cause problems such as contaminating film manufacturing equipment and processing equipment.

The amount of oligomers contained in a film varies depending on the polymer manufacturing conditions, molecular structure of the polymer, molding conditions, thermal history, etc., but if it is contained in a large amount in the starting material polymer, it is not possible to reduce it in the film. It becomes difficult. In such a case, it is necessary to reduce the amount of oligomer contained in the polymer, and a well-known method can be used to reduce the amount of oligomer contained in the polymer. For example, after the polymer is produced, the oligomer is removed by treating the powder preferably with an appropriate organic solvent.

Examples of organic solvents that can be used in this treatment include methylene chloride, chloroform, toluene, xylene, N-methylpyrrolidone, etc., preferably at normal pressure or under pressure.
The treatment is carried out at a temperature of 0°C or higher, more preferably 50°C or higher.

On the other hand, as an example of a method for reducing oligomers during film molding, for example, an extruder equipped with seven or more exhaust vents is used, and the pent part is maintained at a reduced pressure while molding is performed while discharging components such as oligomers. Here are some methods. This method can be employed at any stage, such as the process of forming polymer powder into pellets, or the process of forming polymer powder and/or pellets into a sheet.

Of course, in the present invention, the method for reducing the amount of oligomers contained in the film is not limited to these methods, and methods other than those described above can also be adopted. Other polymers (e.g. polyester, polyamide, polyethylene, polystyrene, polycarbonate, polysulfone, polyethersulfone, polyimide, etc.) and/or 10% by weight or less based on the total amount of sulfide
Organic or inorganic compounds (e.g. calcium terephthalate, calcium oxalate, glass fiber, carbon fiber, talc, kaolin, titanium oxide, silicon oxide, carbon black, calcium carbonate, etc.)
can be contained. Additionally, additives such as antioxidants, heat stabilizers, lubricants, and ultraviolet absorbers may be added as necessary.

The polyphenylene sulfide film of the present invention thus obtained has excellent heat resistance, dimensional stability, mechanical properties, and chemical stability, electrical properties, weather resistance, etc. It can be suitably used for insulating films, capacitor dielectric films, flexible printed circuit boards, thermal transfer films, magnetic recording media films, photographic films, packaging materials, and the like.

In addition, in the present invention, the film thickness is usually O6~/! θμm is preferably in the range of /~roμm.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

The measurement method and evaluation method used in the present invention are as follows.

(1) Amount of oligomer: Cut the sample into small pieces of approximately 100 cm square, and accurately weigh approximately 51 pieces. The sample was placed in a Soxhlet extractor containing about 100,000 liters of methylene chloride, and extracted in a water bath at 60° C. for 24 hours. Thereafter, the solvent of the extract is distilled off under reduced pressure using a pre-weighed tare bag, followed by vacuum drying at 60° C. for 5 hours, and then cooled to room temperature in a desiccator containing silica gel, and the weight is measured.

Apply the obtained results to the following formula to calculate the amount of oligomer (wt%)
seek.

A: Weight of (extract + tare) after drying (1) B: Weight of tare (2) C: Weight of sample before extraction (2) (2) Film density Density gradient tube using lithium bromide aqueous solution I measured it.

(3) Using a melt viscosity enhancement type flow tester, using a nozzle with a diameter of /■ and a length of 70 mm, it was measured at 3θoC and a shear rate of 200 (seconds) -1.

(4) Thermal shrinkage rate The sample was heat-treated for 910 minutes at a predetermined temperature in an atmosphere without tension, and the length of the sample before and after was measured and calculated using the following formula.

Heat shrinkage rate (chi) = (sample length before heat treatment) M x / θ0 (5) Solder bath resistance of the film Cut the film into a square of 20 MRX 20 ra and immerse it in a solder bath at 2jO ℃ for 70 seconds. did. Measure the size of the film after dipping, a mm x b mm,
Calculate the area retention rate using the following formula and measure it as a measure of hanging bath resistance! No points were scored, and the average value was calculated.

(6) Film haze The turbidity of the film was measured according to JIS-47/4t using a sphere-type turbidimeter NDH-20 [manufactured by Nippon Denshoku Kogyo ■].

The measured value of film haze is Hl, and the measured value of haze after applying liquid paraffin to the film surface is internal haze H.
, then the surface haze ΔH is defined by the following formula: ΔH=H1−HO (7) Equipment contamination during film formation Observe the equipment contamination due to oligomers during film formation,
Evaluation was made according to the following criteria.

Rank: Adhesion of oligomers to the roll was observed within 5 hours after the start of film formation.

Rank 2: Adhesion of oligomers to the roll was observed within 1 hour after the start of film formation.

Rank 3 Film production/! No oligomer adhesion even after hours of treatment.

Regarding contamination by oligomers: /) Rotary cooling roll for rapidly cooling and solidifying the molten sheet extruded from the die, 2) Cooling roll on the high speed side during longitudinal roll stretching, and 3) Winding device for stretched film. An evaluation was performed on three locations on the guide roll.

Example/ (Production of polyphenylene sulfide) p-dichlorobenzene, m-') chlorobenzene, /,
2. 'I-trichlorobenzene and sodium sulfide nonahydrate are used as starting materials, m-phenylene sulfide units are contained in block form in 6θ moles, and trifunctional units are θ,
! A polyphenylene sulfide block copolymer containing mulch was obtained. After washing the polymer with water and drying, 4tθ
Extraction treatment was carried out twice with methylene chloride at 1 hour each time, and the mixture was dried again to obtain a white powder polymer (A) having a melt viscosity of 2j-00 poise.

Next, p-dichlorobenzene, /, 2. 'I-trichlorobenzene and sodium sulfide dihydrate as starting materials
Poly p-7 enylene sulfide containing O0J' functional units was produced, washed with water, dried, extracted twice with methylene chloride at 9 to C for 2 hours each time, and dried again to have a melt viscosity of 3! 00 poise white powder polymer (B)
I got it.

Next, 2 parts of polymer (A), 2 parts of polymer (B),
Mixing 0.3 parts of titanium oxide with an average particle size of 0.3 μm,
The mixture was thoroughly kneaded and extruded using a λ-axis extruder equipped with an exhaust vent while exhausting the air, and was formed into pellets.

(Polyphenylene sulfide film + 7) IJ construction)
The composition obtained by the above operation was supplied to a melt extruder, extruded into a sheet from a die with a width of 300 m and a lip interval of oJ mm, and electrostatically charged with a rotating cooling roll whose surface temperature was set to 0°C. Rapidly solidify using the applied cooling method to a thickness of 7.
A substantially amorphous sheet of 00 μm was obtained.

The sheet was then stretched 2 times in the machine direction at 93°C and <1.0 times in the transverse direction at 700°C, and further heat treated at 26θ°C for 70 seconds to obtain a biaxially oriented film with a thickness of 6 μm. .

Table 1 shows the characteristics of the obtained film and the observation results of the roll contamination during film formation.

Example 2 Polymer (33) used in Example / 0θil [0.2 parts of silica particles with an average particle size of 0.9 μm were mixed to prepare a film-forming raw material, and a film with a thickness of 6 μm was prepared in the same manner as in Example /. A biaxially oriented film was produced.

Example 3 Polyphenylene sulfide containing 60 mol of m-7 enylene sulfide monomer (i17'' locking unit) and 0.7 mol % of trifunctional units was prepared in the same manner as the polymer (A) used in Example 3. A block copolymer was obtained.The polymer was washed with water, dried, extracted twice with N→tilpyrrolidone at 60°C for 1 hour each, washed again with water, and dried to obtain a white powder polymer (C). The melt viscosity was 22θθ poise.

Further, in the same manner as polymer (B), 0.
A poly p-phenylene sulfide containing 7 molti was produced. After the polymer was washed with water and dried, it was extracted twice with N-methylpyrrolidone at 10° C. for 2 hours each time, and washed again with water and dried to obtain a white powder polymer (D).

The melt viscosity was 3600 poise.

Next, add 2 parts of polymer (C) and 2 parts of polymer (D)? 2nd part,
Mixing 0.3 parts of titanium oxide with an average particle size of 0.3 μm,
The mixture was thoroughly kneaded and extruded using a coaxial extruder equipped with an exhaust vent while exhausting the air, and was molded into pellets. Using the composition, the thickness O μ was obtained in the same manner as in Example
A biaxially oriented film of m was produced. However, the heat treatment after biaxial stretching was carried out at 24 tO ℃ for 70 seconds, and after cooling, it was further carried out for 10 seconds at 2 tO ℃. It has excellent heat resistance and dimensional stability.

That is, it has a low thermal shrinkage rate and a high area retention rate in terms of solder bath resistance.

In addition, because the content of oligomers is small, there is no contamination of equipment such as rolls during the film-forming process, and the film-forming properties are good, allowing stable film production for long periods of time without problems such as film breakage. .

The surface haze of the obtained film was a low value, and no decrease in transparency due to the oligomer was observed.

Comparative Example/A biaxially oriented film having a thickness of μm was produced in the same manner as in Example/, except that the heat treatment temperature in Example/ was set to 0°C. The obtained film had a low density of 334 tons and was poor in heat resistance and dimensional stability.

Comparative Example A polyphenylene sulfide copolymer (E
), melt viscosity in the same manner as for polymer (B)! Poly p-phenylene sulfy of 30θ poise)' (F) 't'
Profitable.

Next, add ♂ parts of polymer (E), 92 parts of polymer (F),
A biaxially oriented film with a thickness of 33 m was produced in the same manner as in Example 1 by mixing 0.3 parts of titanium oxide with an average particle size of 0.3 μm to prepare a film-forming raw material.

The heat-resistant dimensional stability of the film obtained in Comparative Example 7 was good, but there was some oligomer adhesion to the roll during film formation.
A problem arose in that the film formation had to be frequently interrupted for removal.0 Also, the surface haze of the film showed a large value.

That is, since the oligomer content of the film was high, the oligomer bleed out onto the film surface, resulting in a decrease in the transparency of the film.

〔Effect of the invention〕

The polyphenylene sulfide film of the present invention has excellent heat-resistant dimensional stability and transparency, and is characterized in that there is no contamination of film forming equipment or film processing equipment based on the oligomers it contains, and its industrial value is high.

Applicant: Diafoil Co., Ltd. Agent: Patent Attorney Hase - Others/names

Claims (1)

[Claims] (1) A polyphenylene sulfide film stretched at least uniaxially, in which 70 mol% or more of the film is composed of repeating units ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and the density is 1.340 or more, and A polyphenylene sulfide film having an oligomer content of 1.2% by weight or less.